Braided tubular Structure for a composite part its construction and its applications

ABSTRACT

Braided tubular structure ( 11 ) including longitudinal elongate elements ( 9 ) distributed on a plurality of collars coaxial with the structure and braiding threads ( 8 ) forming two grids of directions oblique in relation to the longitudinal elongate elements and interlaced with the longitudinal elongate elements. The braiding threads following paths which cause them pass between the longitudinal elongate elements. In the tubular structure, the braiding threads ( 8 ) of each one of the grids form an assembly of superposed layers in which the braiding threads ( 8 ) are parallel from one layer to the next.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to braided tubular structures, processesand machines for manufacturing them, and their applications in theconstruction of plane armorings for composite material.

2. Background Art

European Patent EP-A-0 113 196 Published Patent Application No.A-0113196 has already disclosed a braided (and nonwoven) tubularstructure, which is intended to form a composite tubular part afterimpregnation with resin and polymerization of the latter. This tubularstructure includes longitudinal threads (parallel to the axis of saidstructure) and helicoidal braiding threads forming two grids ofdirections oblique in relation to said longitudinal threads, saidbraiding threads being interlaced with one another, as well as with saidlongitudinal threads. These longitudinal threads are distributed on aplurality of collars coaxial with the structure and the helicoidalbraiding threads follow paths which cause them to pass between thelongitudinal threads of one or of a plurality of concentric collars,these paths being such that the projections of said braiding threadsonto a plane orthogonal to the axis of the tubular structure are brokenlines, all the sections of which are oblique in relation to thethickness of the wall of said tubular structure.

It is possible in this way to obtain braided tubular structures ofconsiderable wall thickness. However, in spite of this, the mechanicalwall characteristics of the tubular composite parts constructed fromthese tubular structures are relatively low, since these tubularstructures exhibit numerous voids due to the intersections of the pathsof the helicoidal threads of one and the same direction.

BROAD DESCRIPTION OF THE INVENTION

The object of the present invention is to remedy this disadvantage.

To this end, according to the invention, the braided tubular structureincluding longitudinal elongate elements distributed on a plurality ofcollars coaxial with the structure and braiding threads forming twogrids of directions oblique in relation to said longitudinal elongateelements and interlaced with said longitudinal elongate elements, saidbraiding threads following paths which cause them to pass between saidlongitudinal elongate elements, is noteworthy in that said braidingthreads of each one of said grids form an assembly of superposed layersin which said braiding threads are parallel from one layer to the next.

Thus, said parallel braiding threads, which form layers which aresuperposed in the direction of the thickness of the wall of said tubularstructure, permit the minimization of the intersections and thus theimparting of excellent mechanical properties to said wall.

Said longitudinal elongate elements may be threads as in the Europeanpublished patent application identified hereinabove. They may likewisebe composed of thread rovings, of cables, of rods, of tubes, etc . . . .

In order to be able to construct such a tubular structure, it isadvantageous, in accordance with the present invention, to braid it bymeans of a plurality of braiding threads which are wound off from somany spools which are displaceable through a succession of elementarypaths that said braiding threads should become interlaced with elongateelements which are parallel to one another and distributed on aplurality of coaxial collars. According to the invention, this processis noteworthy in that said spools are displaced with the aid of threetypes of elementary paths, that is to say first elementary paths ofdirection orthogonal in relation to said coaxial collars, secondelementary paths of direction circumferential in relation to the latterand third elementary paths, each one of which associates a first and asecond elementary path inter se.

Thus, said first elementary paths permit said braiding threads to becaused to pass around said elongate elements of different collars, thatis to say within the thickness of the wall of said tubular structure,while said circumferential second paths permit the constitution of saidsuperposed layers formed of threads which are parallel from one layer tothe next.

It will be noted that, by varying the sequence of said elementary paths,it is possible to vary the braiding “mesh”. Thus numerous sequences ofdifferent elementary paths are possible and, by virtue of the invention,it is possible to obtain a large number of different “meshes” for thetubular structure of the present invention.

For the implementation of such a process, the present inventionadvantageously provides a braiding machine including a set of identicalmultiindented wheels, mounted on a fixed support and driven in rotationto cause the circulation of spindles carrying spools of braidingthreads, said multiindented wheels being disposed in parallel andequidistant lines. In order to be capable of executing the three typesof elementary paths which are characteristic of said process, thismachine is, according to the invention, noteworthy:

in that, in said set of multiindented wheels:

the multiindented wheels belonging to a line are spaced from oneanother, so that two consecutive multiindented wheels belonging to oneand the same line cannot cooperate directly with one another;

a multiindented wheel belonging to one line is disposed between twomultiindented wheels belonging to an adjacent line and cooperates withsaid two multiindented wheels; and

in that, in the spaces between the consecutive multiindented wheels of aline, there are provided passages for said longitudinal elongateelements of said braided tubular structure.

The result is accordingly a quincuncial arrangement for themultiindented wheels and for said passages, said quincunces ofmultiindented wheels being overlapped with said quincunces of saidpassages. Within such quincunces, the distance between the centers oftwo consecutive multiindented wheels of a line is equal to the distancebetween two consecutive passages of a line, these distances being equalto twice the distance between two adjacent lines of multiindented wheelsand of passages.

By virtue of such a quincuncial arrangement, it is possible to cause thecirculation of said spindles transversely and parallel to said lines ofmultiindented wheels, and also to cause them to turn about the center ofa multiindented wheel, so that it is possible to execute the three typesof elementary paths mentioned hereinabove.

To do this, according to another feature of the present invention, insaid spaces between the consecutive multiindented wheels of a line,there are further provided rhomboidal needles of controlled orientationwhich are intended to direct said spindles to cause them to pass fromone multiindented wheel to another belonging to an adjacent line (firstand second elementary paths) or to maintain them on their respectivemultiindented wheels (third elementary paths).

Preferably, said needles are coaxial with said passages for the elongateelements, so that they likewise form quincunces, which are superposedupon those of said passages.

Said needles can be controlled in orientation by a linkage gear.

Preferably, at each instant:

all the needles associated with a line of multi-indented wheels areparallel to one another and thus have a common orientation; and

the common orientations of the needles associated with two adjacentlines of multiindented wheels are symmetrical with respect to oneanother in relation to said lines.

Said fixed support of the multiindented wheels may be plane.Nevertheless, for reasons associated with braiding mesh clamping, it isadvantageous that said plane support should be cylindrical. In thiscase, said plane support may be constituted by the internal wall of acylindrical collar. Such a collar may have its axis disposed verticallyor horizontally.

Moreover, French Patents FR-A-2 610 951 and FR-A-2 610 952 have alreadydisclosed a plane woven armoring for composite material including weftthreads distributed on a plurality of superposed levels and warp threadspassing around weft threads situated at different levels. Thus, such anarmoring exhibits high characteristics of delamination. However, onaccount of the fact that threads which make up said armoring follow, ina plane, only two directions (the warp direction and the weftdirection), the composite parts which incorporate it may, for certainapplications, exhibit an insufficient shear modulus, parallel to saidplane.

Thus, the object of the present invention is also to construct such aplane armoring having an improved planar shear modulus.

To this end, according to the invention, the plane armoring forcomposite material including parallel elongate elements distributed on aplurality of superposed levels, in the manner of weft threads, isnoteworthy:

in that it includes:

a first grid of threads which are parallel to one another, passingaround said elongate elements situated at different levels;

a second grid of threads which are parallel to one another, passingaround said elongate elements situated at different levels; and

in that the general directions of the threads of said first and secondgrids are symmetrical with respect to one another in relation to saidparallel elongate elements.

According to the present invention, to obtain such a plane armoring:

initially there is constructed a braided tubular structure includingparallel longitudinal elongate elements distributed on a plurality ofcollars coaxial with the structure and braiding threads which form twogrids of directions oblique and symmetrical in relation to thelongitudinal elongate elements and interlaced with said longitudinalelongate elements, said braiding threads following paths which causethem to pass between said longitudinal elongate elements, so that saidbraiding threads of each one of said grids form an assembly ofsuperposed layers in which said braiding threads are parallel from onelayer to the next; then

said tubular structure is split along a longitudinal cutting lineparallel to said longitudinal elongate elements.

Thus, after the longitudinal cutting of said tubular structure andflattening of the latter, the result obtained is a plane armoring asmentioned hereinabove, in which, on the one hand, said first and secondgrids of parallel threads are constituted respectively by said grids ofbraiding threads and, on the other hand, said parallel elongate elementsdistributed on a plurality of superposed levels are formed by saidlongitudinal elongate elements distributed on the plurality of coaxialcollars of said braided tubular structure.

Thus, such a process permits the construction, by braiding, that is tosay at high speed, of the plane structure according to the invention.The latter can therefore be manufactured more rapidly than theconventional woven armorings, although it exhibits great improvements ascompared with the latter.

It will be noted that, to obtain such a plane armoring, it isadvantageous to make use of the braiding machine specified hereinabove,equipped with cutting means to split longitudinally the braid formed bysaid machine.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures of the accompanying drawing will give a good understandingof how the invention may be performed. In these figures, identicalreferences designate similar elements.

FIG. 1 is a diagrammatic side view of a part of a braiding machineaccording to the present invention.

FIG. 2 is an enlarged partial side view, partly cut away, of the machineof FIG. 1, illustrating the arrangement of the multiindented wheels, thespindles, the directing needles and the thread guides, according to thepresent invention.

FIG. 3 is a partial plan view of the quincuncial arrangement of themultiindented wheels, the spindle roots, the directing needles and thethread guides, according to line III—III of FIG. 2.

FIG. 4 diagrammatically illustrates the quincuncial arrangement of thepinions which are solid with the multiindented wheels.

FIG. 5 diagrammatically shows the control linkage gear of the directingneedles.

FIGS. 6A to 6F diagrammatically illustrate the rectilinear translationalmovement of the spindles orthogonally to the lines of the arrangement ofthe multiindented wheels.

FIGS. 7A and 7B diagrammatically illustrate the result of therectilinear translation of FIGS. 6A to 6F.

FIGS. 8A to 8F diagrammatically illustrate the rectilinear translationalmovement of the spindles parallel to the lines of the arrangement of themulti-indented wheels.

FIGS. 9A and 9B diagrammatically illustrate the result of therectilinear translation of FIGS. 8A to 8F.

FIGS. 10A to 10E diagrammatically illustrate the circular translationalmovement of the spindles permitting the association of the rectilineartranslations of FIGS. 6 and 7 with the rectilinear translations of FIGS.8 and 9.

FIGS. 11A and 11B diagrammatically illustrate the result of the circulartranslation of FIGS. 10A to 10E.

FIGS. 12 and 13 are, respectively, a side view and a diagrammatic frontview of an embodiment of the braiding machine according to the presentinvention.

FIG. 14 is a side elevation view of a diagrammatic modified embodimentof the braiding machine of FIGS. 12 and 13.

FIGS. 15, 16 and 17 show, respectively, examples of braiding meshesaccording to the present invention, in the particular case of astructure incorporating two superposed levels of parallel threads.

FIGS. 18, 19 and 20 illustrate, respectively, the surface appearance ofbraidings obtained by the meshes of FIGS. 15, 16 and 17.

FIGS. 21 and 22 illustrate, diagrammatically, two examples ofdisplacement paths of the spindles to obtain the mesh of FIGS. 15 and18.

FIG. 23 illustrates, in diagrammatic perspective, a braidingincorporating seven levels of longitudinal threads exhibiting the meshof FIGS. 15 and 18.

FIG. 24 illustrates, in diagrammatic perspective, a braiding exhibitingthe mesh of FIGS. 15 and 18 and in which some parallel threads arereplaced by elongate tubular elements.

FIGS. 25 and 26 illustrate, diagrammatically, two examples ofdisplacement paths of the spindles to obtain the mesh of FIGS. 16 and19.

FIG. 27 illustrates, diagrammatically, an example of displacement pathsof the spindles to obtain the mesh of FIGS. 17 and 20.

FIG. 28 illustrates, diagrammatically, yet another example ofdisplacement paths of the spindles for a braiding variant incorporatingseven levels.

FIG. 29 illustrates, in diagrammatic perspective, the seven-levelbraiding obtained by the displacement of the spindles in accordance withFIG. 28.

DETAILED DESCRIPTION OF THE INVENTION

The braiding machine which is diagrammatically and partially representedin FIG. 1 includes a support 1 on which there are journaled a set ofidentical multiindented wheels 2 and on which there are mountedtraversing guidance tubes 3. This machine further includes a braidformation mandrel 4 of longitudinal axis T—T and a mesh formation ring5, which is coaxial with said mandrel.

As is customary, the multiindented wheels 2, which are driven inrotation by means not shown, cause the circulation of spindles 6carrying spools 7 of braiding threads 8. These threads 8 are wound offfrom the spools 7 and pass through the ring 5 and are applied onto themandrel 4. Such spindles 6 are very well known in the art of braidingand, in FIGS. 1 and 2, they are represented only very diagrammatically.

Moreover, threads 9 which are wound off from spools 10 pass through theguidance tubes 3 and the ring 5 and are applied onto said mandrel 4,being disposed parallel to one another and being distributed on aplurality of collars coaxial with the axis T—T.

The multiindented wheels 2, while causing the circulation of thespindles 6 and thus the spools 7 about the axis T—T, interlace thebraiding threads 8 with the parallel threads 9, forming, in a knownmanner, two grids of directions oblique in relation to said parallelthreads 9, said braiding threads 8 following paths which cause them topass between said parallel threads 9.

The result of this, on the mandrel 4, is the progressive formation of abraided tubular structure or braid 11, of axis T—T.

FIGS. 2, 3 and 4 show in greater detail that:

each multiindented wheel 2 is dual and is constituted by two paralleldisks 2A and 2B, which are respectively provided with four radialnotches 12A or 12B regularly distributed at their periphery, each notch12A of the disk 2A being superposed upon a notch 12B of the disk 2B toform an indentation 12 for a wheel 2. Each wheel 2 thus includes fourindentations 12 distributed at 90° at its periphery;

each multiindented wheel 2 is solid with a shaft 13, of axis R—R, whichis journaled in the support 1, by virtue of roller bearings 14; and

a pinion 15 is keyed on each shaft 13.

In addition, according to the invention, it can be seen therein that:

the multiindented wheels 2 are disposed in parallel and equidistantlines L—L;

the multiindented wheels 2 belonging to a line L—L are spaced from oneanother, so that the two pinions 15 associated respectively with twoconsecutive multiindented wheels belonging to one and the same linecannot be in engagement with one another;

a multiindented wheel 2 belonging to one line L—L is disposed betweentwo multiindented wheels 2 belonging to an adjacent line L—L and thethree pinions 15 associated respectively with these three multiindentedwheels mesh with one another. It will be noted that, by virtue of thisparticular feature and the preceding one, two consecutive multiindentedwheels 2 belonging to one and the same line turn in the same direction;

the guidance tubes 3 are disposed in the spaces between themultiindented wheels 2, in such a way that their axes G—G are situatedon said lines L—L, at equal distances from the axes R—R of theconsecutive multiindented wheels 2.

Thus, the multiindented multiindented wheels 2 and the guidance tubes 3are respectively disposed in quincunces, said quincunces beingoverlapped.

Moreover, as can be seen in FIG. 2, each guidance tube 3 is mounted onthe support 1 via a foot 16, which is fixed in said support by a tenon16A. On each foot 16 there is mounted to rotate about the correspondingaxis G—G a jacket 16B which carries, at its upper part, a directingfinger 17 in the form of a rhomboidal needle (see also FIG. 3) and, atits lower part, a control tab 18 (see also FIG. 5).

For the control of the orientation of said needles 17, the machineincludes a linkage gear including a common sliding bar 19 and aplurality of sliding bars 20, which are parallel to one another butorthogonal to the common bar 19. Each one of the bars 20 is articulated,at one of its ends, to the common bar 19 via a rocker bar 21, so thatsaid bars 20 are driven in translation parallel to their longitudinalaxis (arrows f) when said common bar 19 is displaced parallel to itslongitudinal axis (arrow F).

Each bar 20 is intended for the control of the needles 17 of twoconsecutive lines L—L, so that the control tabs 18, associated withthese two lines of needles, are articulated by their free ends, at 18A,to said bar 20.

Furthermore, the arrangement of said control tabs 18 on the bars 20 issuch that:

all the needles 17 of a line are parallel to each other and remainparallel to each other when they turn about their respective axes G—G,under the action of the corresponding sliding bar 20, which is itselfdriven to slide by the common bar 19;

the needles 17 belonging to two adjacent lines L—L are symmetrical withrespect to one another in relation to the lines and turn while remainingsymmetrical, when the common blade 19 slides.

Thus, the common orientation of the needles 17 of a line L—L issymmetrical with respect to the common orientation of the needles 17 ofan adjacent line L—L, and all the needles 17 of one line L—L in two areparallel to one another.

The total amplitude of rotation of each needle 17, under the action ofthe sliding of the common blade 19, may be in the order of 60°.

In customary fashion, each spindle 6 is provided with a foot 22 which iscapable of being grasped by an indentation 12 of a wheel 2 to permit thedisplacement of said spindles in relation to said set of multiindentedwheels, under the control of the needles 17, as is described hereinbelowwith reference to FIGS. 6 to 11.

FIGS. 6A to 6F and 7A, 7B illustrate a first elementary path for thedisplacement of the spindles 6. FIGS. 6A to 6F show a group of fourmultiindented wheels 2.1 to 2.4 and five needles 17.1 to 17.5 disposedin such a manner that:

the multiindented wheel 2.1 and the needles 17.1 and 17.2 are disposedon a line L1—L1, said needles being adjacent to said wheel and placed oneither side of the latter;

the multiindented wheels 2.2 and 2.3 and the needle 17.3 are disposed ona line L2—L2 adjacent to the line L1—L1, said wheels being adjacent tosaid needle and placed on either side of the latter;

the multiindented wheel 2.4 and the needles 17.4 and 17.5 are disposedon a line L3—L3 adjacent to the line L2—L2, said needles being adjacentto said wheel and placed on either side of the latter; and

the pinions 15 (not shown) of the multiindented wheels 2.1 to 2.4cooperate with one another, as is illustrated in FIG. 4.

Furthermore, in FIG. 6A, which illustrates an initial condition, it hasbeen assumed that:

the needles 17.1, 17.2, 17.4 and 17.5 exhibit an orientation, regulatedby the linkage gear 19, 20, such that they make an angle A close to 75°in relation to their respective line L1—L1 or L3—L3;

the needle 17.3 exhibits an orientation, regulated by the linkage gear19, 20, such that it makes an angle B close to 105° in relation to theline L2—L2;

each one of the multiindented wheels 2.1 to 2.4 exhibits two alignedindentations on the line L1—L1, L2—L2 or L3—L3, respectively;

spindle feet 22.1, 22.2, 22.3 and 22.4 are situated respectively on thelines L1—L1, L2—L2 and L3—L3, the foot 22.1 (in engagement with themultiindented wheel 2.1) being opposite the needle 17.1, while the feet22.2 and 22.3 (in engagement with the multiindented wheels 2.2 and 2.3respectively) are situated to the side of the needle 17.3 and the foot22.4 (in engagement with the multiindented wheel 2.4) is opposite theneedle 17.5; and

the multiindented wheel 2.1 turns in a counterclockwise direction, sothat the same applies to the multiindented wheel 2.4 and the twomultiindented wheels 2.2 and 2.3 turn in a clockwise direction.

Furthermore, in FIGS. 6A to 6F, it is assumed that the needles 17.1 to17.5 maintain a fixed orientation, as described hereinabove.

In these circumstances, as soon as the multiindented wheels 2.1 to 2.4turn, they bring the feet 22.1 and 22.4 into contact with the needle17.3 and the feet 22.2 and 22.3, respectively, into contact with theneedles 17.4 and 17.2 (see FIG. 6B). As the rotation of saidmultiindented wheels continues, indentations of different multiindentedwheels come opposite said feet 22.1 to 22.4 and the needles 17.2, 17.3and 17.4 push said feet 22.1 to 22.4 so as to cause them to penetrateinto the indentation of another multiindented wheel and, accordingly, tocause them to change multiindented wheel.

On examining the successive steps illustrated by FIGS. 6C, 6D, 6E and6F, it is possible to establish that:

the foot 22.1 passes from the multiindented wheel 2.1 to themultiindented wheel 2.2,

the foot 22.2 passes from the multiindented wheel 2.2 to themultiindented wheel 2.4,

the foot 22.3 passes from the multiindented wheel 2.3 to themultiindented wheel 2.1,

the foot 22.4 passes from the multiindented wheel 2.4 to themultiindented wheel 2.3.

When all the multiindented wheels have turned through a quarterrevolution (FIG. 6F), all the feet 22.1 to 22.4 have executed anelementary translational path t1, orthogonal to said lines L1—L1, L2—L2and L3—L3 and of amplitude equal to the distance between said lines, asis clearly illustrated in FIGS. 7A and 7B, which respectively illustratethe initial positions (FIG. 7A) and the final positions (FIG. 7B)corresponding to FIGS. 6A and 6F respectively.

Through this elementary path t1, the feet 22.1 and 22.2 have movedfurther away from the line L1—L1 in the direction of the line L3-L3,while the feet 22.3 and 22.4 have moved away from the line L3-L3 in thedirection of the line L1—L1.

FIGS. 8A to 8F and 9A, 9B illustrate a second elementary path for thedisplacement of the spindles 6. FIGS. 8A to 8F show a group of fourmultiindented wheels 2.5 to 2.8 and five needles 17.6 to 17.10,respectively disposed on lines L4—L4, L5—L5 and L6—L6, in a similarmanner to the arrangement of the multiindented wheels 2.1 to 2.4 and ofthe needles 17.1 to 17.5 on the lines L1—L1, L2—L2 and L3—L3, as shownin FIGS. 6A to 6F.

In FIG. 8A, which illustrates an initial condition:

the needles 17.6, 17.7, 17.9 and 17.10 have an orientation, imposed bythe linkage gear 19, 20, such that they make an angle C close to 165° inrelation to their respective line L4—L4 or L6—L6;

the needle 17.8 has an orientation, such that it makes an angle D closeto 15° in relation to the line L5—L5;

each one of the multiindented wheels 2.5 to 2.8 exhibits twoindentations aligned perpendicularly to said lines L4—L4, L5—L5 orL6—L6;

spindle feet 22.5 to 22.8 are situated respectively in suchindentations, in such a manner that:

the foot 22.5, in engagement with the multiindented wheel 2.5, issituated between the needles 17.6 and 17.8;

the foot 22.6, in engagement with the multiindented wheel 2.7, issituated between the needles 17.7 and 17.8;

the foot 22.7, in engagement with the multiindented wheel 2.6, issituated between the needles 17.8 and 17.9;

the foot 22.8, in engagement with the multiindented wheel 2.8, issituated between the needles 17.8 and 17.10.

Furthermore, in FIGS. 8A to 8F, the needles 17.6 to 17.10 maintain afixed orientation, corresponding respectively to the angles C or D, andthe multiindented wheel 2.5 turns in a clockwise direction, so that thesame applies to the multiindented wheel 2.8, and the multiindentedwheels 2.6 and 2.7 turn in a counterclockwise direction.

In these circumstances, as soon as the multiindented wheels 2.5 to 2.8turn, they bring the foot 22.5 into abutment against the needle 17.6,the foot 22.8 into abutment against the needle 17.10 and the feet 22.6and 22.7 into abutment against the needle 17.8 (see FIG. 8B). As therotation of the multiindented wheels continues, indentations ofdifferent multiindented wheels come opposite said feet 22.5 to 22.8 andthe needles 17.6, 17.8 and 17.10 push said feet 22.5 to 22.8 so as tocause them to penetrate into the indentation of another multiindentedwheel and, accordingly, to cause them to change multiindented wheel.

On examining the successive steps illustrated by FIGS. 8C to 8F, it canbe established that:

the foot 22.5 passes from the multiindented wheel 2.5 to themultiindented wheel 2.6,

the foot 22.6 passes from the multiindented wheel 2.7 to themultiindented wheel 2.5,

the foot 22.7 passes from the multiindented wheel 2.6 to themultiindented wheel 2.8,

the foot 22.8 passes from the multiindented wheel 2.8 to themultiindented wheel 2.7.

Thus, when all the multiindented wheels 2.5 to 2.8 have turned through aquarter revolution (FIG. 8F), all the feet 22.5 to 22.8 have executed anelementary translational path t2, parallel to said lines L4—L4, L5—L5and L6—L6 and of amplitude equal to the distance between said lines, asis clearly illustrated in FIGS. 9A and 9B, which show, respectively, theinitial positions (FIG. 9A) at the final positions (FIG. 9B)corresponding to FIGS. 8A and 8F respectively.

Through this elementary path t2, the feet 22.5 and 22.6 were displacedtowards the left in the figures, while the feet 22.7 and 22.8 weredisplaced towards the right in the figures.

FIGS. 10A to 10E and 11A, 11B illustrate a third elementary path for thedisplacement of the spindles 6. FIGS. 10A to 10E show a group of fourmultiindented wheels 2.9 to 2.12 and five needles 17.11 to 17.15,respectively disposed on lines L7—L7, L8—L8 and L9—L9, in a similarmanner to the arrangement of the multiindented wheels 2.1 to 2.4 and ofthe needles 17.1 to 17.5 on the lines L1—L1, L2—L2 and L3—L3, asrepresented in FIGS. 6A to 6F.

In FIG. 10A, which illustrates an initial condition:

the needles 17.11, 17.12, 17.14 and 17.15 have an orientation, imposedby the linkage gear 19, 20, such that they make an angle E close to 45°in relation to their respective line L7—L7 or L9—L9;

the needle 17.13 has an orientation, such that it makes an angle F closeto 135° in relation to the line L8—L8;

each one of the multiindented wheels 2.9 to 2.12 exhibits twoindentations aligned with the lines L7—L7, L8—L8 or L9—L9;

spindle feet 22.9 to 22.12 are situated respectively in suchindentations, in such a manner that:

the foot 22.9, in engagement with the multiindented wheel 2.9, issituated between the needles 17.11 and 17.13;

the foot 22.10, in engagement with the multiindented wheel 2.10, issituated between the needles 17.13 and 17.14;

the foot 22.11, in engagement with the multiindented wheel 2.11, issituated between the needles 17.12 and 17.13;

the foot 22.12, in engagement with the multiindented wheel 2.12, issituated between the needles 17.13 and 17.15.

In FIGS. 10A to 10F, the multiindented wheel 2.9 turns in acounterclockwise direction, so that the same applies to themultiindented wheel 2.12 and the multiindented wheels 2.10 and 2.11 turnin a clockwise direction. Furthermore, in the execution of said thirdelementary path, the needles are controlled in orientation by thelinkage gear 19, 20, so that the angles E and F change respectively frominitial values approximately equal to 45° and 135° (FIG. 10A) to finalvalues approximately equal to 15° and 165° (FIG. 10E).

In these circumstances, as soon as the multiindented wheels 2.9 and 2.12and the needles 17.11 to 17.15 start to turn, the feet 22.9 and 22.12are supported against the needle 17.13, while the feet 22.10 and 22.11come respectively into abutment against the needles 17.14 and 17.12.Each one of said feet 22.9 to 22.12 is then obliged to remain within theindentation within which it was initially accommodated, without anypossibility of changing multiindented wheels.

Thus, when all the multiindented wheels 2.9 to 2.12 have turned througha quarter revolution (FIG. 10E), all the feet 22.9 to 22.12 havelikewise turned through a quarter revolution, about the axis of theirrespective multiindented wheels, so that each one of them has executedan elementary rotational path r through a quarter turn, either in aclockwise direction (22.9 and 22.10) or in a counterclockwise direction(22.11 and 22.12), as is clearly illustrated in FIG. 11A and 11B, whichshow, respectively, the initial positions (Figure 11A) and the finalpositions (FIG. 11B) corresponding to FIGS. 10A and 10E respectively.

From the a foregoing, it will readily be understood:

a) that a first elementary path t1 exhibits a direction parallel to thethickness of the wall of the braid 11, that is to say orthogonal to thecoaxial collars of threads 9, so that a thread 8, which is wound offfrom a spool 7 displaced in accordance with such an elementary path t1,exhibits a section which, in projection orthogonal to the axis T—T, islikewise orthogonal to said coaxial collars;

b) that a plurality of elementary paths t1 may be concatenated insuccession, to vary the length of said section of said thread 8orthogonal to said collars;

c) that a second elementary path t2 exhibits a direction circumferentialin relation to said braid 11 and to said coaxial collars of threads 9,so that a thread 8, which is wound off from a spool 7 displaced inaccordance with such an elementary path t2, exhibits a section which, inprojection orthogonal to the axis T—T, is likewise circumferential tosaid braid;

d) that a plurality of elementary paths t2 may be concatenated insuccession, to vary the length of said circumferential section of thread8; and

e) that a third elementary path r permits the association of a firstpath t1 with a second path t2 and vice versa, so that it is possible tocause a thread 8 to follow a continuous path composed of sectionscorresponding to the elementary paths t1 and to the elementary paths t2,associated inter se.

Thus, said first elementary paths t1 are utilized to displace thebraiding threads 8 between the parallel threads 9 of the coaxialcollars, while said second elementary paths t2 are utilized to form thebraiding proper with said threads 8. It will be noted that, as thelatter are all circumferential in relation to the braid (and not obliquein relation to the thickness of the wall of the braid, as in EuropeanPublished Patent Application No. A-0113196), said braiding threads 8 ofeach one of the two grids of the braid 11 form an assembly of superposedlayers in which said braiding threads 8 are parallel from one layer tothe next.

In the machine diagrammatically described with reference to FIGS. 1 to5, it has been implicitly assumed that the support 1 of themultiindented wheels 2 is plane. On the other hand, FIGS. 12 and 13 showdiagrammatically a machine according to the present invention in whichsaid support is formed by a fixed cylindrical collar 30, of horizontalaxis H—H.

In the embodiment of FIGS. 12 and 13, the traversing guidance tubes 3and the spindles 6, carrying the spools 7, are mounted on the internalwall 31 of the collar 30 (for the sake of clarity, the multiindentedwheels 2 are not shown). Of course, in this case, it is necessary, inthe construction and the assembly of the multiindented wheels 2, thepinions 15 and the tubes 3, to take account of the circular concavity ofthe internal wall 31.

The mandrel 4 is disposed coaxially with the collar 30 and the spools 10of the threads 9 are mounted in creels 32 dispersed laterally (not shownin FIG. 12).

The machine of FIGS. 12 and 13 further includes, downstream of themandrel 4, a cutting device 33 to split the braid 11 longitudinally,that is to say parallel to the threads 9 of said braid. The result isaccordingly a plane web 34, which can be wound onto a drum 35. Thus,such a plane web 34 constitutes a plane armoring including parallelthreads 9 distributed on a plurality of superposed levels (each levelcorresponding to a coaxial collar of threads 9 of the braid 11), as wellas two grids of threads 8 passing about said parallel threads 9, whichare such that, in each one of said grids of threads 8, the latter areparallel to one another and that the general directions of the threads 8of these two grids of threads are symmetrical with respect to oneanother in relation to the parallel threads 9.

FIG. 14 illustrates a variant of the machine of FIGS. 12 and 13, inwhich variant the traversing guidance tubes 3 and the spindles 6 aremounted on the internal wall 41 of a collar 40, of vertical axis V—V.The mandrel 4 is then disposed vertically, coaxially with the collar 40.This FIG. 14 again shows the creels 32 and the cutting device 33. Thelatter permits the production, from the braid 11, of the plane web 34which is wound onto the drum 35.

FIGS. 15, 16 and 17 illustrate, respectively, three examples of mesh forthe braid 11 or the armoring 34, in the simplified case where there areonly two coaxial collars (or two superposed levels) of parallel threads9. In these figures, which substantially correspond to sectionsorthogonal to said parallel threads 9, it has been assumed that threads8 of the two grids of oblique threads were visible in the plane of thesection. FIGS. 18, 19 and 20 illustrate the surface appearance of thebraidings corresponding, respectively, to the meshes of FIGS. 15, 16 and17.

Moreover, FIGS. 21 and 22 illustrate, in superposition upon a plandiagram of the quincuncial arrangement of the multiindented wheels 2 andthe parallel threads 9, two possibilities of paths Tr1 and Tr2 for thespindles 6 carrying the threads 8, for the purpose of obtaining thebraiding mesh illustrated in FIGS. 15 and 18. It is easily verified thateach one of the paths Tr1 and Tr2 is composed only of sequences of thefirst, second and third elementary paths t1, t2 and r, as illustrated inFIGS. 7B, 9B and 11B.

FIG. 23 diagrammatically illustrates, in perspective, with a cutaway, abraid 11 or an armoring 34 corresponding to another example of braidingwith the mesh of FIGS. 15 and 18. This braiding includes sevensuperposed levels of threads 9 and, if the direction of the threads 9 istaken to be equal to 0°, it further comprises three laps of threads 8 at+α° and three laps of threads 8 at −α°. The angle α is, for example,equal to 60°.

In the modified embodiment of the braiding of FIG. 23, which modifiedembodiment is illustrated by FIG. 24, some parallel threads 9 have beenreplaced by tubes 50, which are parallel to one another and to saidthreads 9. The result of this is a structure comparable with a honeycombstructure.

FIGS. 25 and 26 illustrate, in a view comparable with FIGS. 21 and 22,two possibilities of paths Tr3 and Tr4 for the spindles 6 carrying thethreads 8, for the purpose of obtaining the braiding mesh of FIGS. 16and 19.

FIG. 27 illustrates, in a view comparable with FIGS. 21, 22, 24 and 25,paths Tr5 for the spindles 6, for the purpose of obtaining the braidingmesh of FIGS. 17 and 20.

Finally, FIG. 28 illustrates, in a view comparable with FIGS. 21, 22,24, 25 and 27, paths Tr6 for the spindles 6, for the purpose ofobtaining the braiding variant incorporating seven levels which isillustrated in diagrammatic perspective in FIG. 29.

It will be readily understood from the aforegoing that, given the largenumber of possible combinations of the first, second and thirdelementary paths t1, t2 and r, the examples of braiding meshes, ofbraided structures and of paths of spindles which are shown by FIGS. 15to 27 are only possibilities among others, and that these examples donot restrict the possibilities of the present invention.

What is claimed is:
 1. A braided tubular structure (11) includinglongitudinal elongate elements (9) distributed on a plurality of collarscoaxial with structure and helical braiding threads (8) forming twogrids of directions oblique in relation to said longitudinal elongateelements and wound around and interlaced with said longitudinal elongateelements, said longitudinal elongate elements being selected from amongthe elements of a group consisting of threads, thread rovings, cables,rods and tubes, said helical braiding threads following paths whichcause them to pass between said longitudinal elongate elements, wherein,in projection orthogonal to said longitudinal elongate elements (9),said paths of said helical braiding threads are constituted by: firstelementary paths (t1) having a direction parallel to the thickness ofthe wall of the tubular structure (11) and orthogonal to the coaxialcollars of elongate elements (9); second elementary paths (t2) having adirection circumferential in relation to said coaxial collars ofelongate elements (9); and third elementary paths (r) connecting firstelementary paths (t1) to second elementary paths (t2), in such a waythat said helical braiding threads (8) of each one of said grids form anassembly of superposed layers in the direction of the thickness of thewall of said tubular structure 11, in which layers said helical braidingthreads (8) are parallel from one layer to the next, wherein thebraiding threads are all circumferential in relation to the braid and sothat each of the braiding threads does not pass completely through thethickness of the wall of the tubular structure.